add 4bits_bin

src/io/bin.cpp

@@ -2,6 +2,7 @@
 #include <LightGBM/bin.h>
 
 #include "dense_bin.hpp"
+#include "dense_nbits_bin.hpp"
 #include "sparse_bin.hpp"
 #include "ordered_sparse_bin.hpp"
 
@@ -277,14 +278,15 @@ Bin* Bin::CreateBin(data_size_t num_data, int num_bin, double sparse_rate,
 }
 
 Bin* Bin::CreateDenseBin(data_size_t num_data, int num_bin) {
-  if (num_bin <= 256) {
+  if (num_bin <= 16) {
+    return new Dense4bitsBin(num_data);
+  } else if (num_bin <= 256) {
     return new DenseBin<uint8_t>(num_data);
   } else if (num_bin <= 65536) {
     return new DenseBin<uint16_t>(num_data);
   } else {
     return new DenseBin<uint32_t>(num_data);
   }
-
 }
 
 Bin* Bin::CreateSparseBin(data_size_t num_data, int num_bin) {

src/io/dense_bin.hpp

@@ -67,7 +67,7 @@ class DenseBin : public Bin {
     HistogramBinEntry* out) const override {
     // use 4-way unrolling, will be faster
     if (data_indices != nullptr) {  // if use part of data
-      const data_size_t rest = num_data % 4;
+      const data_size_t rest = num_data & 0x3;
       data_size_t i = 0;
       for (; i < num_data - rest; i += 4) {
         const VAL_T bin0 = data_[data_indices[i]];
@@ -97,7 +97,7 @@ class DenseBin : public Bin {
         ++out[bin].cnt;
       }
     } else {  // use full data
-      const data_size_t rest = num_data % 4;
+      const data_size_t rest = num_data & 0x3;
       data_size_t i = 0;
       for (; i < num_data - rest; i += 4) {
         const VAL_T bin0 = data_[i];

src/io/dense_nbits_bin.hpp

@@ -0,0 +1,260 @@
+#ifndef LIGHTGBM_IO_DENSE_NBITS_BIN_HPP_
+#define LIGHTGBM_IO_DENSE_NBITS_BIN_HPP_
+
+#include <LightGBM/bin.h>
+
+#include <vector>
+#include <cstring>
+#include <cstdint>
+
+namespace LightGBM {
+
+class Dense4bitsBin;
+
+class Dense4bitsBinIterator: public BinIterator {
+public:
+  explicit Dense4bitsBinIterator(const Dense4bitsBin* bin_data, uint32_t min_bin, uint32_t max_bin, uint32_t default_bin)
+    : bin_data_(bin_data), min_bin_(static_cast<uint8_t>(min_bin)),
+    max_bin_(static_cast<uint8_t>(max_bin)),
+    default_bin_(static_cast<uint8_t>(default_bin)) {
+    if (default_bin_ == 0) {
+      bias_ = 1;
+    } else {
+      bias_ = 0;
+    }
+  }
+  inline uint32_t Get(data_size_t idx) override;
+  inline void Reset(data_size_t) override { }
+private:
+  const Dense4bitsBin* bin_data_;
+  uint8_t min_bin_;
+  uint8_t max_bin_;
+  uint8_t default_bin_;
+  uint8_t bias_;
+};
+
+class Dense4bitsBin: public Bin {
+public:
+  friend Dense4bitsBinIterator;
+  Dense4bitsBin(data_size_t num_data)
+    : num_data_(num_data) {
+    int len = (num_data_ + 1) / 2;
+    data_ = std::vector<uint8_t>(len, static_cast<uint8_t>(0));
+  }
+
+  ~Dense4bitsBin() {
+
+  }
+
+  void Push(int, data_size_t idx, uint32_t value) override {
+    if (buf_.empty()) {
+#pragma omp critical
+      {
+        if (buf_.empty()) {
+          int len = (num_data_ + 1) / 2;
+          buf_ = std::vector<uint8_t>(len, static_cast<uint8_t>(0));
+        }
+      }
+    }
+    const int i1 = idx >> 1;
+    const int i2 = (idx & 1) << 2;
+    const uint8_t val = static_cast<uint8_t>(value) << i2;
+    if (i2 == 0) {
+      data_[i1] = val;
+    } else {
+      buf_[i1] = val;
+    }
+  }
+
+  void ReSize(data_size_t num_data) override {
+    if (num_data_ != num_data) {
+      num_data_ = num_data;
+      int len = (num_data_ + 1) / 2;
+      data_.resize(len);
+    }
+  }
+
+  BinIterator* GetIterator(uint32_t min_bin, uint32_t max_bin, uint32_t default_bin) const override;
+
+  void ConstructHistogram(const data_size_t* data_indices, data_size_t num_data,
+    const score_t* ordered_gradients, const score_t* ordered_hessians,
+    HistogramBinEntry* out) const override {
+    if (data_indices != nullptr) {  // if use part of data
+
+      const data_size_t rest = num_data & 0x3;
+      data_size_t i = 0;
+
+      for (; i < num_data - rest; i += 4) {
+
+        data_size_t idx = data_indices[i];
+        const auto bin0 = (data_[idx >> 1] >> ((idx & 1) << 2)) & 0xf;
+
+        idx = data_indices[i + 1];
+        const auto bin1 = (data_[idx >> 1] >> ((idx & 1) << 2)) & 0xf;
+
+        idx = data_indices[i + 2];
+        const auto bin2 = (data_[idx >> 1] >> ((idx & 1) << 2)) & 0xf;
+
+        idx = data_indices[i + 3];
+        const auto bin3 = (data_[idx >> 1] >> ((idx & 1) << 2)) & 0xf;
+
+
+        out[bin0].sum_gradients += ordered_gradients[i];
+        out[bin1].sum_gradients += ordered_gradients[i + 1];
+        out[bin2].sum_gradients += ordered_gradients[i + 2];
+        out[bin3].sum_gradients += ordered_gradients[i + 3];
+
+        out[bin0].sum_hessians += ordered_hessians[i];
+        out[bin1].sum_hessians += ordered_hessians[i + 1];
+        out[bin2].sum_hessians += ordered_hessians[i + 2];
+        out[bin3].sum_hessians += ordered_hessians[i + 3];
+
+        ++out[bin0].cnt;
+        ++out[bin1].cnt;
+        ++out[bin2].cnt;
+        ++out[bin3].cnt;
+
+      }
+
+      for (; i < num_data; ++i) {
+        const data_size_t idx = data_indices[i];
+        const auto bin = (data_[idx >> 1] >> ((idx & 1) << 2)) & 0xf;
+        out[bin].sum_gradients += ordered_gradients[i];
+        out[bin].sum_hessians += ordered_hessians[i];
+        ++out[bin].cnt;
+      }
+    } else {  // use full data
+      const data_size_t rest = num_data & 0x3;
+      data_size_t i = 0;
+      for (; i < num_data - rest; i += 4) {
+        int j = i >> 1;
+        const auto bin0 = (data_[j]) & 0xf;
+        const auto bin1 = (data_[j] >> 4) & 0xf;
+        ++j;
+        const auto bin2 = (data_[j]) & 0xf;
+        const auto bin3 = (data_[j] >> 4) & 0xf;
+
+        out[bin0].sum_gradients += ordered_gradients[i];
+        out[bin1].sum_gradients += ordered_gradients[i + 1];
+        out[bin2].sum_gradients += ordered_gradients[i + 2];
+        out[bin3].sum_gradients += ordered_gradients[i + 3];
+
+        out[bin0].sum_hessians += ordered_hessians[i];
+        out[bin1].sum_hessians += ordered_hessians[i + 1];
+        out[bin2].sum_hessians += ordered_hessians[i + 2];
+        out[bin3].sum_hessians += ordered_hessians[i + 3];
+
+        ++out[bin0].cnt;
+        ++out[bin1].cnt;
+        ++out[bin2].cnt;
+        ++out[bin3].cnt;
+      }
+      for (; i < num_data; ++i) {
+        const auto bin = (data_[i >> 1] >> ((i & 1) << 2)) & 0xf;
+        out[bin].sum_gradients += ordered_gradients[i];
+        out[bin].sum_hessians += ordered_hessians[i];
+        ++out[bin].cnt;
+      }
+    }
+  }
+
+  virtual data_size_t Split(
+    uint32_t min_bin, uint32_t max_bin, uint32_t default_bin,
+    uint32_t threshold, data_size_t* data_indices, data_size_t num_data,
+    data_size_t* lte_indices, data_size_t* gt_indices) const override {
+    if (num_data <= 0) { return 0; }
+    uint8_t th = static_cast<uint8_t>(threshold + min_bin);
+    uint8_t minb = static_cast<uint8_t>(min_bin);
+    uint8_t maxb = static_cast<uint8_t>(max_bin);
+    if (default_bin == 0) {
+      th -= 1;
+    }
+    data_size_t lte_count = 0;
+    data_size_t gt_count = 0;
+    data_size_t* default_indices = gt_indices;
+    data_size_t* default_count = &gt_count;
+    if (default_bin <= threshold) {
+      default_indices = lte_indices;
+      default_count = &lte_count;
+    }
+    for (data_size_t i = 0; i < num_data; ++i) {
+      const data_size_t idx = data_indices[i];
+      const auto bin = (data_[idx >> 1] >> ((idx & 1) << 2)) & 0xf;
+      if (bin > maxb || bin < minb) {
+        default_indices[(*default_count)++] = idx;
+      } else if (bin > th) {
+        gt_indices[gt_count++] = idx;
+      } else {
+        lte_indices[lte_count++] = idx;
+      }
+    }
+    return lte_count;
+  }
+  data_size_t num_data() const override { return num_data_; }
+
+  /*! \brief not ordered bin for dense feature */
+  OrderedBin* CreateOrderedBin() const override { return nullptr; }
+
+  void FinishLoad() override {
+    int len = (num_data_ + 1) / 2;
+    for (int i = 0; i < len; ++i) {
+      data_[i] |= buf_[i];
+    }
+    buf_.clear();
+  }
+
+  void LoadFromMemory(const void* memory, const std::vector<data_size_t>& local_used_indices) override {
+    const uint8_t* mem_data = reinterpret_cast<const uint8_t*>(memory);
+    if (!local_used_indices.empty()) {
+      for (int i = 0; i < num_data_; ++i) {
+        // get old bins
+        const data_size_t idx = local_used_indices[i];
+        const auto bin = (mem_data[idx >> 1] >> ((idx & 1) << 2)) & 0xf;
+        // add
+        Push(0, i, bin);
+      }
+    } else {
+      for (size_t i = 0; i < data_.size(); ++i) {
+        data_[i] = mem_data[i];
+      }
+    }
+  }
+
+  void CopySubset(const Bin* full_bin, const data_size_t* used_indices, data_size_t num_used_indices) override {
+    auto other_bin = reinterpret_cast<const Dense4bitsBin*>(full_bin);
+    for (int i = 0; i < num_used_indices; ++i) {
+      const data_size_t idx = used_indices[i];
+      const auto bin = (other_bin->data_[idx >> 1] >> ((idx & 1) << 2)) & 0xf;
+      Push(0, i, bin);
+    }
+  }
+
+  void SaveBinaryToFile(FILE* file) const override {
+    fwrite(data_.data(), sizeof(uint8_t), data_.size(), file);
+  }
+
+  size_t SizesInByte() const override {
+    return sizeof(uint8_t) * data_.size();
+  }
+
+protected:
+  data_size_t num_data_;
+  std::vector<uint8_t> data_;
+  std::vector<uint8_t> buf_;
+};
+
+uint32_t Dense4bitsBinIterator::Get(data_size_t idx) {
+  const auto bin = (bin_data_->data_[idx >> 1] >> ((idx & 1) << 2)) & 0xf;
+  if (bin >= min_bin_ && bin <= max_bin_) {
+    return bin - min_bin_ + bias_;
+  } else {
+    return default_bin_;
+  }
+}
+
+BinIterator* Dense4bitsBin::GetIterator(uint32_t min_bin, uint32_t max_bin, uint32_t default_bin) const {
+  return new Dense4bitsBinIterator(this, min_bin, max_bin, default_bin);
+}
+
+}  // namespace LightGBM
+#endif   // LIGHTGBM_IO_DENSE_NBITS_BIN_HPP_

windows/LightGBM.vcxproj

@@ -216,6 +216,7 @@
     <ClInclude Include="..\src\boosting\goss.hpp" />
     <ClInclude Include="..\src\boosting\score_updater.hpp" />
     <ClInclude Include="..\src\io\dense_bin.hpp" />
+    <ClInclude Include="..\src\io\dense_nbits_bin.hpp" />
     <ClInclude Include="..\src\io\ordered_sparse_bin.hpp" />
     <ClInclude Include="..\src\io\parser.hpp" />
     <ClInclude Include="..\src\io\sparse_bin.hpp" />

windows/LightGBM.vcxproj.filters

@@ -174,6 +174,9 @@
     <ClInclude Include="..\src\boosting\goss.hpp">
       <Filter>src\boosting</Filter>
     </ClInclude>
+    <ClInclude Include="..\src\io\dense_nbits_bin.hpp">
+      <Filter>src\io</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\src\application\application.cpp">